The objective of the proposed research is to improve the chemotherapy of malignant diseases through a better understanding of the pharmacology and mode of action of the clinically effective antitumor agents, cyclophosphamide, bischloroethylnitrosourea (BCNU), and L-phenylalanine mustard. In recent years the nature of the alkylating moieties derived in the body from cyclophosphamide and BCNU have been elucidated, in part through work accomplished under our previous grant CA-16783. In this application for continuation of support we propose to continue our chemical studies with the alkylating entities and to complete our studies of their reaactions with nucleic acids, nucleotides, and nucleosides. Identification of the alkylated nucleic acid components is primarily by mass spectrometry. The functional significance of these alkylation reactions will be sought in studies of the structure of the alkylated nucleic acids and of the nucleic acid metabolism of cells containing the alkylated nucleic acids. We will continue to measure levels of cyclophosphamide and its metabolites in patients by gas chromatography-selective ion monitoring and to attempt to relate these levels to our chemical and biochemical studies in order to understand the therapeutic and toxic effects of this drug in man. In addition to our studies on cyclophosphamide and BCNU we plan to initiate studies with L-phenylalanine mustard. In particular, we are developing a gas chromatography-selective ion monitoring assay to utilize in patients receiving this drug. We plan to study the reactions of L-phenylalanine mustard with nucleic acid components and to compare these results with those obtained from the studies with cyclophosphamide and BCNU.